When interaction takes place elliptical galaxies can become spirals and vice versa

Since galaxies are now known to travel the universe in clusters , and since they appear to be moving away from each other (indicating that the universe is expanding , collisions and interactions are quite common between galaxies . Here is where the shapes change the most . It is thought that a galaxy on its own with no interaction is not likely to change shape , although it is thought that irregular galaxies are very young and unstructured in addition to being unstable . But

there is nothing to indicate that an irregular galaxy will ever be anything else and an irregular galaxy can be the end result of a collision that destabilized both galaxies involved

One note of interest regarding the evolution of galaxies is that spiral galaxies are capable of producing new stars as long as there is sufficient interstellar hydrogen in the stellar arms . Elliptical galaxies are devoid of these gases , so they do not produce new stars The production of new stars , however , has no bearing on the shape of the galaxy

The distribution of matter in the universe is now known to be the biggest factor in galactic evolution (U .S . DOE , 2003 . In observing the two types of galaxies (red and blue , researchers with the Sloan Digital Sky Survey (SDSS ) have discovered that clustering properties of the two types of galaxies do not appear to be continuous , as was previously thought . This has enormous bearing on how galaxies evolve and change shape , and in what sequence

The red (elliptical ) galaxies do tend to be older , and the blue (spiral ) galaxies appear to be more active with new star formations Elliptical galaxies also tend to be found in areas with denser matter as opposed to the spirals , which...